Cooling jacket for a gasification burner

Abstract

A feed injector for a gasifier includes a burner and a cooling jacket protecting the burner from high temperatures. The cooling jacket includes two concentric channels to provide a flow path for a heat transfer fluid (typically water) to travel through one channel toward the front of the burner, along the front of the burner, and back through the other channel. Heat transfer in the cooling jacket is improved by introducing one or more fins in the path of the heat transfer fluid and / or by increasing the radius of curvature of the wall angles bordering the recirculation zone in the cooling jacket.

Description

Background Technology

[0001] This invention relates to a method and apparatus for protecting a burner used in the partial combustion (or gasification) of solid carbonaceous fuels. Specifically, the invention relates to the design and use of a cooling jacket to protect the burner during partial combustion using an oxygen-containing gas and a fuel stream comprising finely separated solid carbonaceous fuel carried by a fluid to produce syngas containing carbon monoxide and hydrogen. The syngas product is commonly used as fuel gas or as a feedstock in chemical processes.

[0002] As used herein, the term "solid carbonaceous fuel" is intended to include various carrier gas combustible materials and mixtures thereof, and may be selected from the group consisting of coal, coke from coal, coal liquefaction residues, petroleum coke, coal dust, biomass, and particulate solids derived from oil shale, tar sands, and bituminous pitch. Coal may be of any type, including lignite, sub-bituminous coal, bituminous coal, and anthracite. Solid carbonaceous fuel preferably has a particle size distribution in which at least about 90% by weight of the material has an average particle size of less than 90 micrometers and a moisture content of less than about 5% by weight. Solid carbonaceous fuel may be delivered to the burner as a suspension in a fluid such as a carrier gas or a liquid slurry.

[0003] As used herein, the term “oxygen-containing gas” is intended to refer to a gas containing free oxygen (O2) and includes air, oxygen-enriched air (i.e., containing more than 21 mol% oxygen), and substantially pure oxygen (i.e., containing more than about 95 mol% oxygen), with other components including gases commonly found in air, such as nitrogen and / or rare gases.

[0004] The partial combustion or gasification of solid carbonaceous fuels such as coal to produce gases that have value as residential and industrial fuels, as starting materials for synthetic chemicals and fuels, and as energy sources for power generation has long been recognized and practiced on a global scale.

[0005] At the exhaust end of a gasification burner, combustion temperatures can reach 1300°C or higher. During prolonged operation, this leads to thermal stress and degradation, particularly fatigue stress, on the burner front or surface, potentially causing coolant leakage. Furthermore, the burner head also experiences high mechanical pressure loads during operation. For these reasons, a cooling jacket is desirable, as it reduces both the metal temperature and its fluctuations, thereby minimizing thermal stress and extending the burner's service life.

[0006] Hasenack et al. (US 4,887,962) taught a cooling jacket with a spiral flow path inside the tip, which is said to maximize the flow rate of water and dissipate heat to the maximum extent.

[0007] Van Der Ploeg et al. (WO 2009 / 019272) taught a cooling jacket in which the cross-sectional area is reduced before the cooling water enters the front of the burner and is said to result in increased flow rate and lower pressure drop.

[0008] Effective operation of a cooling jacket requires maximizing the flow rate of the heat transfer fluid to remove as much heat as possible from the vaporizer. However, a reflux zone can form, where the heat transfer fluid is effectively trapped, leading to hot spots and mechanical failures. There is a need in the art for a cooling jacket design that minimizes or even eliminates the formation of reflux zones to maximize heat transfer within the cooling jacket. Summary of the Invention

[0009] The purpose of this invention is to extend the service life of the burner by minimizing both the temperature of the metal at the front of the burner and temperature changes.

[0010] The present invention includes a cooling jacket device and an operating method to minimize pressure drop while improving fluid flow near the front of the burner.

[0011] Aspect 1: A feed injector for gasifying a feed stream containing a solid carbonaceous fuel, the feed injector comprising a burner and a cooling jacket surrounding the burner; wherein the cooling jacket comprises a conical inner wall, a tip wall, a conical outer wall, and an inner cone; wherein the conical inner wall is connected to the tip wall at a corner, the tip wall is connected to the conical outer wall, and the inner cone is surrounded by the conical inner wall, the tip wall, and the conical outer wall; including an internal channel for a heat transfer fluid inlet defined by the space between the conical inner wall and the inner cone; wherein a recirculation zone is in fluid flow communication with the tip channel and The space between the inner wall of the conical head, the tip wall, and the point of the inner cone closest to the corner of the wall is defined; the tip channel, which is in fluid flow communication with the reflux zone, is defined by the space between the tip wall and the inner cone; the outer channel, which is in fluid flow communication with the tip channel, is defined by the space between the outer wall of the conical head and the inner cone; the thickness of the inner channel is defined by the distance from the inner wall of the conical head to the inner cone; and the ratio of the thickness of the inner channel at the heat transfer fluid inlet to the thickness of the inner channel at the interface with the reflux zone is between 1.5 and 3.

[0012] Aspect 2: The feed injector according to aspect 1 further includes one or more fins extending into the inner channel and / or recirculation zone.

[0013] Aspect 3: The feed injector according to aspect 2, wherein the length of one or more fins is between 1 mm and 4 mm.

[0014] Aspect 4: The feed injector according to aspect 2 or aspect 3, wherein the one or more fins comprise a single continuous circular structure.

[0015] Aspect 5: The feed injector according to aspect 1 further includes one or more fins attached to the inner wall of the conical head and extending into the recirculation zone.

[0016] Aspect 6: The feed injector according to aspect 5, wherein the length of one or more fins is between 1 mm and 4 mm.

[0017] Aspect 7: The feed injector according to aspect 5 or aspect 6, wherein the one or more fins comprise a single continuous circular structure.

[0018] Aspect 8: The feed injector according to any one of aspects 1 to 7, wherein the wall corner has a radius of curvature measured in a radial cross section at the interface with the recirculation zone, the radius of curvature being between 0.5 mm and 4 mm.

[0019] Aspect 9: The feed injector according to any one of aspects 1 to 8, wherein the thickness of the tip wall is between 1 mm and 8 mm.

[0020] Aspect 10: The feed injector according to any one of aspects 1 to 9 further includes a refractory pad in contact with the outer surface of the outer wall of the conical head.

[0021] Aspect 11: A method of operating a feed injector for a gasifier, the method comprising supplying a heat transfer fluid through an internal channel having flow restriction to increase the linear velocity of the heat transfer fluid, and heating the heat transfer fluid by direct contact with a tip wall; wherein the tip wall has a highest temperature and a lowest temperature along the interface between the tip wall and the heat transfer fluid; and the temperature difference between the highest temperature and the lowest temperature is less than 150°C.

[0022] Aspect 12: The method according to aspect 11, wherein the highest temperature at the interface between the tip wall and the heat transfer fluid is less than 190°C.

[0023] Aspect 13: The method according to aspect 11 or aspect 12, wherein the pressure of the heat transfer fluid is 0 bar to 10 bar greater than the pressure in the vaporizer.

[0024] Aspect 14: The method according to any one of aspects 11 to 13, wherein the pressure of the heat transfer fluid is about 10 bara.

[0025] Aspect 15: The method according to any one of aspects 11 to 14, wherein the ratio of the linear velocity of the heat transfer fluid at the inlet of the inner channel to the linear velocity of the heat transfer fluid at the outlet of the inner channel is between 1.3 and 2.8. Attached Figure Description

[0026] The invention will now be described with reference to the accompanying drawings, wherein the same numbers denote the same elements.

[0027] Figure 1 A cooling jacket according to the present invention is shown.

[0028] Figure 2 It shows Figure 1 A modification of the embodiment, wherein the cooling jacket has fins protruding into the heat transfer fluid flow path near the outlet of the inner channel.

[0029] Figure 3 It shows Figure 1 Modification of the embodiment, wherein the wall corners of the cooling jacket have a greater than Figure 1 A larger radius of curvature.

[0030] Figure 4 It shows Figure 2 Modification of the embodiment, wherein the wall corners of the cooling jacket have a greater than Figure 2 A larger radius of curvature. Detailed Implementation

[0031] The following detailed description provides only preferred exemplary embodiments and is not intended to limit the scope, applicability, or configuration of the invention. Rather, the subsequent detailed description of preferred exemplary embodiments will provide those skilled in the art with a feasible description for implementing the preferred exemplary embodiments of the invention. As set forth in the appended claims, various changes may be made to the function and arrangement of the elements without departing from the spirit and scope of the invention.

[0032] The feed injector used in the gasification process typically includes a burner and a cooling jacket surrounding the burner.

[0033] A burner typically includes a series of concentric channels to deliver one or more carbonaceous fuel streams and one or more oxygen-containing streams to the gasifier.

[0034] The cooling jacket includes two concentric channels to provide flow paths for the heat transfer fluid (typically water) to travel through one channel toward the front of the burner, along the front of the burner, and return through the other channel. At higher process temperatures, steam can be used as the heat transfer fluid. The heat transfer fluid can travel through the outer channel toward the front of the burner and return via the inner channel, but in a preferred embodiment, it travels through the inner channel toward the front of the burner and returns via the outer channel.

[0035] Cooling jackets can comprise a single component or multiple connectors for ease of construction and / or maintenance. For example, a cooling jacket can be constructed by mounting a conical head to a cylindrical block with two concentric annular channels via a perforated connector to allow heat transfer fluid to pass through. This provides a stable mounting for the conical head, which has thinner walls for better heat transfer, but at the cost of reduced physical strength.

[0036] Figure 1 A radial cross-section along the axis of rotation of the cooling jacket 1 according to the invention is shown. As used herein, a radial cross-section is defined as a plane passing through the axis of rotational symmetry, while a circular cross-section is defined as a plane perpendicular to the axis of rotational symmetry. The walls of the cooling jacket 1 can be defined as follows: the inner wall 11 of the conical head is closest to the burner 10 and is physically connected to the tip wall 12. The term "physical connection" as used herein includes two characteristics: two or more parts of a single component, or two or more components connected by means such as welding. The tip wall 12 is typically the thinnest wall in the cooling jacket because it is connected to the high-temperature vaporizer and must transfer as much heat as possible to the heat transfer fluid to avoid damaging the feed injector 1. Engineering trade-offs are typically required to make the tip wall 12 as thin as possible while still handling the pressure difference between the heat transfer fluid and the vaporizer. The physical connection between the inner wall 11 of the conical head and the tip wall 12 forms a wall corner 14 and can be a joint where two or more components meet, or a transition zone within a single component. The tip wall 12 is also physically connected to the outer wall 16 of the conical head. An inner cone 18 is located in the space between the inner wall 11 and the outer wall 16 of the conical head. The thickness of the inner cone 18 can be varied to affect the flow rate of the heat transfer fluid.

[0037] The flow path of the heat transfer fluid is defined by the walls of the cooling jacket. The inner channel 20 is defined by the space between the inner wall 10 of the conical head and the inner cone 18. The tip channel 22 is defined by the space between the tip wall 12 and the inner cone 18. The outer channel 24 is defined by the space between the outer wall 16 of the conical head and the inner cone 18. A reflux zone 26 is formed at or near the intersection of the inner channel and the tip channel. The reflux zone 26, defined by a plane perpendicular to the inner wall, intersects with the end of the inner cone, and the plane perpendicular to the tip wall intersects with the end of the inner cone, the tip wall, and the inner wall.

[0038] Computational fluid dynamics (CFD) modeling has shown that the behavior of the heat transfer fluid in the recirculation zone 26 is a key determinant of burner lifespan. Specifically, localized hot spots form when the flow separates and dead zones are created near the wall corner 14, preventing the heat transfer fluid from carrying away heat from the tip wall 12 and even leading to boiling. The objective of this invention is to improve the flow in the recirculation zone 26 and minimize or eliminate any dead zones. This improved flow results in lower temperatures at the interface between the tip wall 12 and the heat transfer fluid, as well as a smaller temperature difference between the highest and lowest temperatures within the tip wall 12, which in turn reduces thermal stress and extends burner lifespan.

[0039] One way to improve flow in the recirculation zone 26 is to increase the velocity of the heat transfer fluid by creating a flow restriction 28 in the inner channel 20 near the recirculation zone 26. One way to create the flow restriction 28 is to increase the thickness of the inner cone 18 near its tip. Because the flow restriction also increases the pressure drop, it is best placed near the outlet of the inner channel to minimize the pressure drop. The degree of flow restriction can be measured by the ratio of the thickness of the inner channel at the inlet to the thickness of the inner channel at the interface with the recirculation zone 26. CFD modeling indicates that the optimal ratio for improving flow in the recirculation zone is between 1.5 and 3. Alternatively, the degree of flow restriction can be measured by the ratio of the linear velocity of the heat transfer fluid at the outlet of the inner channel to the linear velocity of the heat transfer fluid at the inlet of the inner channel. CFD modeling indicates that the optimal ratio for improving the linear velocity of the heat transfer fluid in the recirculation zone is between 1.3 and 2.8.

[0040] Figure 2 A cooling jacket 2 is shown, which includes another structural element for improving flow in the recirculation zone 26. One or more fins 30 are oriented such that they extend into the flow path of the heat transfer fluid in the inner channel 20 or the recirculation zone 26, and the length of the fin is defined as the distance the fin extends into the flow path of the heat transfer fluid in a direction perpendicular to the wall. The one or more fins 30 may have a range of radial cross-sectional shapes sufficient to achieve the desired results, including but not limited to triangular, rectangular, or any other shape, particularly shapes that are easy to process into or attach to the wall. When using more than one fin, the fins may have the same or different dimensions and may have the same or different cross-sectional shapes. The one or more fins 30 may be discrete fins arranged circumferentially along the wall, or preferably a single continuous structure attached to the wall. The one or more fins 30 may be attached to the inner wall 10 of the conical head or the inner cone 18. Preferably, the one or more fins 30 are a single continuous structure attached to the inner wall of the conical head and located in the recirculation zone.

[0041] CFD modeling has also shown that the geometry of the corner 14 has a significant impact on the flow pattern of the heat transfer fluid in the recirculation zone 26. When viewed along the radial cross-section, the radius of curvature of the corner 14 is generally the smallest, which results in a thinner tip wall 12 near the corner 14. However, CFD modeling shows that a larger radius of curvature leads to less flow separation along the corner, higher heat transfer fluid velocities, and lower tip wall temperatures despite the thicker tip wall 12. Figure 3 An embodiment of the invention is shown, wherein... Figure 1 Compared to the radius of curvature of approximately 0.5 mm, the radius of curvature of corner 14 is larger, approximately 2.0 mm. The radius of curvature ranges from 0.5 mm to 4.0 mm, or from 1.25 mm to 1.5 mm.

[0042] Each of the fins and rounded corners increases the tip wall temperature, but as Figure 4 As shown, greater improvements can be achieved by combining the two.

[0043] The embodiments described herein offer several advantages over the prior art, which typically uses a spiral coil design in the burner front. In such designs, the spiral tip is usually welded to the burner front, leading to a number of potential problems, including cracking at irregular welds, thermal fatigue of the inner edge of the cooling front, and corrosion near the connection between the spiral tip and the main flange. High-alloy materials have been used to prevent corrosion; however, this also results in high costs. The cooling jacket of this invention is expected to have a longer service life without requiring such expensive materials.

[0044] The cooling jacket is located within the reactor dome and is surrounded by refractory material. A suitable interface is required between the dome refractory material and the cooling jacket, especially in modifications where the cooling jacket has an external pouring plug and internal anchors, to protect the jacket. Spiral coil designs typically cannot anchor the cooling jacket to the pouring plug, which shortens the cooling jacket's service life.

[0045] A typical mitigation measure for higher temperatures in a cooling jacket is to thicken the tip wall to maintain strength at higher metal temperatures. The improved heat transfer in the cooling jacket of this invention allows for the use of thinner walls because the metal has higher strength at lower temperatures, likely due to narrow internal channels, cooling fins, and rounded tip angles. Tip wall thicknesses achievable through improved flow in the recirculation zone range from 1 mm to 8 mm, or from 1.5 mm to 4 mm.

[0046] The increased wall strength also allows the cooling jacket to operate at higher pressures. Typically, the heat transfer fluid is water at 0 to 10 barg, but this invention allows operation at even higher pressures, offering several benefits. For example, operating at pressures 0 to 10 bar higher than the vaporizer pressure provides safety benefits, as any leaks will result in harmless water entering the vaporizer without allowing flammable syngas to enter the cooling water system and pose a risk of fire or explosion. Furthermore, the pressurization within the cooling jacket provides greater structural stability for a given wall thickness, thereby improving the cooling jacket's performance and service life.

[0047] Example

[0048] Assuming the vaporizer combustion temperature outside the tip wall and the outer surface of the outer channel extending 50 mm rearward from the burner surface remains constant at 1371℃, Figure 1-4 The four cooling jacket embodiments shown were modeled using CFD. Cooling water at 43°C and 10 barg was fed into the inner channel at a mass flow rate of 11.34 kg / s. Furthermore, for... Figure 1 The design was modeled for a 50% increase in the mass flow rate of the cooling water to 17.01 kg / s. Table 1 shows the highest temperature, the range between the highest and lowest temperatures on the inner surface of the tip wall, and the pressure drop for each of the five examples.

[0049] As can be seen, Example 2 reduced the highest tip wall temperature and the range of tip wall temperatures, but at the cost of more than doubling the pressure drop. Examples 3-5 reduced the highest tip wall temperature without increasing the cooling water flow rate. As shown in Example 3, introducing 1mm circular fins reduced the tip wall temperature more than in Example 2, with a lower pressure drop. In Example 4, a 2mm radius fillet was more effective, with the same pressure drop as in Example 1, but a lower tip wall temperature. Finally, in Example 5, the lowest tip wall temperature was observed by combining a 2mm radius fillet and 1mm circular fins.

[0050] Table 1

[0051]

[0052] Although the principles of the invention have been described above in conjunction with preferred embodiments, it should be clearly understood that this description is by way of example only and not as a limitation on the scope of the invention.

Claims

1. A feed injector for gasifying a feed stream containing a slurry of solid carbonaceous fuel, the feed injector comprising: The burner and the cooling jacket surrounding the burner; The cooling jacket includes a conical head inner wall, a tip wall, a conical head outer wall, and an inner cone; The inner wall of the conical head is connected to the tip wall at the corner, the tip wall is connected to the outer wall of the conical head, and the inner cone is surrounded by the inner wall of the conical head, the tip wall, and the outer wall of the conical head. This includes an internal channel for the heat transfer fluid inlet defined by the space between the inner wall of the conical head and the internal cone; The reflux zone is in fluid flow communication with the tip channel and is defined by the space between the inner wall of the conical head, the tip wall, and the point of the inner cone closest to the corner of the wall; The tip channel, which is in fluid flow communication with the reflux zone, is defined by the space between the tip wall and the inner cone. The outer channel, which is in fluid flow communication with the tip channel, is defined by the space between the outer wall of the conical head and the inner cone. The thickness of the inner channel is defined by the distance from the inner wall of the conical head to the inner cone. and The ratio of the thickness of the inner channel at the heat transfer fluid inlet to the thickness of the inner channel at the interface with the reflux zone is between 1.5 and 3. The thickness of the internal cone can be varied to affect the flow rate of the heat transfer fluid.

2. The feed injector of claim 1, further comprising one or more fins extending into the inner channel and / or recirculation zone.

3. The feed injector according to claim 2, wherein the length of the one or more fins is between 1 mm and 4 mm.

4. The feed injector of claim 2, wherein the one or more fins comprise a single continuous circular structure.

5. The feed injector of claim 1, further comprising one or more fins attached to the inner wall of the conical head and extending into the recirculation zone.

6. The feed injector according to claim 5, wherein the length of the one or more fins is between 1 mm and 4 mm.

7. The feed injector of claim 5, wherein the one or more fins comprise a single continuous circular structure.

8. The feed injector of claim 1, wherein the wall corner has a radius of curvature measured along a radial cross section at the interface with the recirculation zone, the radius of curvature being between 0.5 mm and 4 mm.

9. The feed injector according to claim 1, wherein the thickness of the tip wall is between 1 mm and 8 mm.

10. The feed injector according to claim 1, further comprising a refractory pad in contact with the outer surface of the outer wall of the conical head.

11. A method of operating a feed injector for a gasifier, the method comprising: The heat transfer fluid is supplied through an internal channel with flow restriction to increase the linear velocity of the heat transfer fluid, wherein the flow restriction is created by increasing the thickness of an internal cone near the tip wall, wherein the thickness of the internal channel is defined by the distance from the inner wall of the conical head to the internal cone, and wherein the ratio of the thickness of the internal channel at the heat transfer fluid inlet to the thickness of the internal channel at the interface with the recirculation zone is between 1.5 and 3. The heat transfer fluid is heated by direct contact with the tip wall; The tip wall has a highest temperature and a lowest temperature along the interface between the tip wall and the heat transfer fluid; and The temperature difference between the highest temperature and the lowest temperature is less than 150°C.

12. The method of claim 11, wherein the highest temperature along the interface between the tip wall and the heat transfer fluid is less than 190°C.

13. The method of claim 11, wherein the pressure of the heat transfer fluid is 0 bar to 10 bar greater than the pressure in the vaporizer.

14. The method of claim 11, wherein the pressure of the heat transfer fluid is approximately 10 bara.

15. The method of claim 11, wherein the ratio of the linear velocity of the heat transfer fluid at the inlet of the inner channel to the linear velocity of the heat transfer fluid at the outlet of the inner channel is between 1.3 and 2.8.

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